Was ‘Reefer Madness’ right?
Alex Berenson says we’re ignoring the dangers of marijuana
IN THE MID-1930s, a church group financed a film intended to frighten parents about the dangers their children face from marijuana. Reefer Madness portrayed cannabis as a powerful drug capable of sending users into psychotic, violent rages. The movie has become something of a cult classic in recent decades, mocked as a laughable example of anti-drug fearmongering over a fairly benign substance, something that sends users into a mellow haze, not violent outbursts.
The film seems even more dated today, as the country appears to be fast moving toward full legalization of marijuana. In November, Massachusetts became the latest state where the doors opened on retail pot sales following voter approval of legalization in 2016. We’re now one of 10 states plus the District of Columbia with legalized recreational sales, and two dozen other states allow some form of medical marijuana sales.
The first Boston-area store opens on Saturday in Brookline. And with organizers expecting upwards of 10,000 people to descend on the Hynes Convention Center this weekend for the fifth annual New England Cannabis Convention, where every conceivable pot-related product will be on display, marijuana is quickly getting as baked into the culture and economy as craft breweries and summer beer gardens.
But what if Reefer Madness was right all along?
The title of his book was the working title for Reefer Madness before the film’s release. While Berenson chose to play off the movie’s original name, he says there is a big difference between the alarms the film sounded more than 80 years ago and his book: “The science didn’t exist then,” he says an interview.
Berenson says there is now clear evidence that marijuana use increases the risk of developing schizophrenia. He further claims that, because of the known connection between schizophrenia and violence, pot use may be responsible for an increase in violent crime in places where it’s been legalized.
The strongest evidence by far on marijuana and mental health, Berenson writes, came two years ago, when the National Academies of Sciences, Engineering, and Medicine issued a report assembled by a committee of 16 experts distilling all the available evidence on the health effects of cannabis.
Despite claims of benefits of marijuana on everything from fighting cancer to improving eczema, the committee concluded there was only strong evidence of three clear benefits: treatment of chronic pain, relieving chemotherapy-induced nausea, and reducing spasms among patients with multiple sclerosis.
As for harms, the report devotes an entire chapter to potential mental health effects, including schizophrenia. The report’s language, frankly, is muddled, something that has helped fuel the contentious back-and-forth that has ensued between Berenson and his critics.
What’s clear is that cannabis use is strongly associated with schizophrenia: Regular cannabis users have much higher rates of the illness than non-users. The debate centers on the crucial question of causality. Does cannabis use cause the development of schizophrenia? Or does the link actually move in the other direction, with those suffering from schizophrenia more likely to use cannabis? That would make cannabis use an effect, not a cause, of schizophrenia.
But the report goes on to suggest that the nature of the association is, in fact, much less clear, saying, “the relationship between cannabis use and cannabis use disorder, and psychoses may be multidirectional and complex,” making it hard “to determine causality and/or directionality in associations between substance use and mental health outcomes. This is a complex issue, one that certainly warrants further investigation.”
That uncertainty was part of the argument put forward by Gov. Charlie Baker, Attorney General Maura Healey, and Boston Mayor Marty Walsh in a Globe op-ed they coauthored in 2016 urging voters not to support full legalization of pot. They cautioned that research was increasingly “showing a frightening correlation between regular marijuana use and severe mental health issues.”
One further sign of the uncertainty about marijuana’s effects comes in the state’s required labeling of marijuana products. Unlike the clear label warnings, for example, about cigarettes causing cancer and heart disease, the mandated warning on marijuana products sold in Massachusetts makes clear just how much we don’t know.
“This product has not been analyzed or approved by the FDA,” reads the required warning. “There is limited information on the side effects of using this product, and there may be associated health risks,” it reads, going on to caution against using marijuana while pregnant or breastfeeding.
Shaleen Title, a member of the state Cannabis Control Commission, said regulators take seriously potential health concerns about marijuana and have a research team they look to for new information that may come to light. But Title, who wrote a letter to the editor of the New York Times in response to a January op-ed Berenson wrote summarizing his argument, defends the move to legalize pot. “Any potential harm caused is far outweighed by the harms of prohibition, stigmatization, and criminalization,” she said in an interview.
Berenson’s book has prompted a slew of articles digging into his main hypothesis. They include a roundtable discussion via email with Berenson and several research experts conducted by The Marshall Project, a nonprofit journalism site focused on criminal justice issues, and a New Yorker piece by Malcolm Gladwell that gave a good deal of credence to Berenson’s warnings. “For the moment, cannabis probably belongs in the category of substances that society permits but simultaneously discourages,” Gladwell wrote.
Lots of the reaction, however, has been much less favorable, with many articles accusing Berenson of wildly overstating research findings of marijuana’s harms while underplaying the damage drug laws have done to minority communities that have borne the brunt of the decades-long war on drugs.
Berenson even loses a potential ally, Vox writer German Lopez, who says he has “become increasingly skeptical of drug legalization over the years” and thinks there are “risks to marijuana that are worth taking seriously, even if one thinks that legalization is ultimately a better policy than prohibition.” Despite sympathizing with Berenson’s broader message that we’re not taking the potential dangers of pot seriously, Lopez ends up panning his book, writing that it “is essentially an exercise in cherry-picking data and presenting causation as correlation.”
Plenty of people aren’t sold on Berenson’s thesis. But with seemingly no end to the claims of marijuana’s benefits — a Worcester start-up is now touting a cannabis-infused gel as a possible female Viagra — his book, at a minimum, is a valuable cautionary tale of its potential downsides.
Berenson freely admits that his is not a balanced account. He says there is no shortage of places to read about the wonders marijuana will bring to everything from urban unemployment to curing celiac disease. He says he set out to tell the other side of the marijuana story. “Not balanced doesn’t mean inaccurate, dishonest, or in any way untruthful,” he writes.
I spoke with him by phone from New York City. What follows is an edited transcript of our conversation.
COMMONWEALTH: Your book has set off quite a ruckus with its claims about marijuana being far from innocuous. Can you lay out the primary claim of the book?
ALEX BERENSON: The primary thesis of the book is that cannabis has a lot of psychiatric dangers that are being undersold by advocates or completely ignored by advocates in their efforts to legalize the drug. The medical benefits of cannabis are far overstated by advocates. That’s important. But even more important is this issue around marijuana and mental illness. What I really focus on is the link between marijuana and psychosis and marijuana and schizophrenia.
CW: The title of the book, Tell Your Children, was the original working title for the film Reefer Madness, in the 1930s, which has been ridiculed as sort of over-the-top fearmongering. You seem to be poking marijuana advocates in the eye with the title, but now some critics are saying the book is appropriately titled because you’re kind of rehashing — if you will – the same sort of wild overstatements as the movie itself.
BERENSON: Yeah. Only I have the science on my side. The science didn’t exist then. I also titled the book that because I think parents need to be able to talk to their kids about this. And there are a lot of parents out there right now who have, you know, 16-, 17-, 18-year-old kids. Especially in the last 12 to 24 months with what’s happened with vaping and Juul, which is a true gateway to THC vaping. There’s a lot of parents who are, like, “I don’t understand what’s going on with my kid and marijuana.” I want them to have some tools to talk to their kids. The book has 60-plus studies in it. Scientists from all over the world are quoted. There’s good evidence that the best way to educate kids about drugs is to take them seriously and talk to them as adults. And that’s what the book tries to do.
CW: Speaking of studies, I was looking for an index or a bibliography in your book, and didn’t find it.
BERENSON: That’s probably the best complaint that I’ve gotten about the book. It could use a bibliography, which I’ve been promising to put up on my website and am going to do. And when we get to a paperback maybe I’ll try to put in an index.
CW: So what does the evidence tell us?
BERENSON: I would say it’s beyond dispute that marijuana can cause temporary psychosis. It can cause temporary psychotic episodes — and frequently does. There is substantial-to-conclusive evidence that marijuana, especially if you use it a lot, especially in your adolescence, substantially increases the risk of schizophrenia, which is really the most severe mental illness, a permanent psychotic disorder. Most people with schizophrenia suffer tremendously and most of the time they don’t get married. They don’t have kids. They never work. They suffer and society suffers with them and their families suffer. Since the Lancet study in 1987 [research on Swedish military recruits published in the British medical journal of that name], this association has been out there in a powerful way.
CW: Is this the one from Sweden?
BERENSON: That’s the one from Sweden. And the work that’s been done in the last three years has essentially said, well, can we separate correlation and causation here? The Lancet study proved correlation and strongly suggested causation. But the work that’s been done since then has been work around causation. When people say, oh, it’s just sort of statistical epidemiological evidence, they’re wrong and they’re misstating the strength of the evidence. They’re substantially understating it.
CW: You point to this National Academies of Sciences report from just two years ago that put together a panel of experts, who in turn marshaled all of the available research studies on cannabis they could. That seems to be a cornerstone of what you’re saying has been the strong new evidence that marijuana, in fact, causes schizophrenia. But there’s been controversy because some members of that committee who wrote the report say there really only was a conclusion of an association of marijuana use of schizophrenia, and that the causal direction is unclear or it’s multidirectional. So it kind of brings us back to back to where we started. In fact, in your book you explained the difference between findings that can be useful for hypothesis testing versus those that are more useful for hypothesis generation. The critique of the book would be that you’ve conflated those and that really the evidence that you point to as a test of the hypothesis is actually just generating a hypothesis to test.
BERENSON: So I have to correct you. It’s not that members of the committee have criticized the report. One of the 16 members, who works for a cannabis research initiative at UCLA that openly solicits money from cannabis investors and users, had said that the report doesn’t say what it says. I would urge you to read chapter 12 yourself. It’s extremely clear.
CW: I did read it, and I was also able to reach the chair of the National Academies committee, Marie McCormick, who’s an emeritus professor at the Harvard School of Public Health. She also said she thinks there has been confusion around this question about causation versus correlation and she subscribes to the same view — that the report concluded there was a correlation between marijuana use and schizophrenia. I did point out to her that I think there is confusion in some of the language. Certainly the summary talks about marijuana use increasing the risk [of schizophrenia]. That, I said to her, doesn’t sound like just correlational language. But it’s also true that elsewhere in the chapter it says that it’s very unclear and there is talk about the causal relationship possibly being multidirectional, including whether it’s kind of a shared genetic predisposition to both schizophrenia and cannabis use. They raise all those.
BERENSON: I would agree that the chapter does raise these. But it raises them in the context of extremely clear language about the link. Listen, if the National Academy of Medicine decides that it wants to update its report, I will write about that. But the report says what it says. You know, lung surgeons were talking about tobacco causing lung cancer in the 1940s. It took at least 20 years for mainstream scientists to follow that and another 30 years for the culture to get there. In that time tens of millions of American lives were lost because of cigarette smoking. So we can choose to say, you know, maybe Berenson’s wrong about this. Maybe all these clinicians are wrong about this. Maybe they’re just seeing the people who are twisted and would’ve been twisted anyway. But it strikes me that the risk is all the other way.
BERENSON: Meaning, we don’t have to legalize this drug, we don’t have to encourage use of it. We’re choosing to go down a path that, if the book is correct, will lead to untold misery for tens of thousands, if not hundreds of thousands, of people. We haven’t even talked about the violence.
CW: So I was going to ask about that next. It’s sort of the next link on the causal chain that you write about in terms of schizophrenia leading to violence.
BERENSON: So, unfortunately, this is even more clear. Schizophrenia is a serious risk for violent crime. The best studies show that people with schizophrenia are at about 20 times greater risk of committing homicide compared to healthy people. That’s an unfortunate fact, and it’s a fact that mental illness advocacy groups don’t like talking about because they fear it stigmatizes people with mental illness and, you know, that may be true. But not talking about this and pretending that it doesn’t exist, unfortunately, puts the families of these people, who are the most likely to be injured or killed by them, at risk. That’s the scary part. The good part of this equation is, when people with schizophrenia are taking antipsychotic medicine, when they’re in treatment, when they’re not using recreational drugs, they’re not that much more violent than healthy people. The studies that I’ve seen suggest that they might be twice as violent, and people as a whole are not that violent, so that’s not that violent. The violence risk is all mediated by being untreated and by using recreational drugs, and the drugs that people with mental illness use more than any other drug is cannabis. And there is really good data showing that a large number of the murders that people with psychotic diseases commit, they’re committing when they’re under the influence of cannabis. It’s not from the US. It’s from Australia and Britain and other places that have taken a more serious look at this than we have.
CW: I also read something pointing out, however, that there has been a pretty steady increase in marijuana use in the US since the 1990s, and that overlaps with a period in which we saw a big drop in violent crime, including homicide, throughout the country.
BERENSON: So crime is multifactorial, right? The number one thing you could do to eliminate violent crime and murders in the United States would be eliminate firearms, right? I mean, we’ve known that would eliminate, I don’t know, 60 or 80 percent of the homicides in the United States tomorrow. So I am not saying that cannabis use is responsible for every homicide in the United States, but what I am saying is that, on an individual basis, there is an appreciable increase in homicide risk and in violent crime risk in people with mental illness who are using cannabis.
CW: At one point in the book you said that marijuana advocates have been “desperate to hide the evidence of its harm.” How do you account for how we’ve gotten to where we are now with this kind of broad move toward legalization, which just landed here in Massachusetts, and that the kinds of concerns you’re raising have not made it into much of the debate?
BERENSON: Cannabis is a really interesting drug. In 2017, 85 percent of the country didn’t use it, even once, and 10 years ago, 90 percent of the country didn’t use it even once in a year. It’s a drug that most people don’t use and half the country has never used and a lot of people who might have used it a handful of times in the ‘70s, ‘80s, or ‘90s used a version of the drug that was much less powerful than what people are using today and probably had minor impacts from it. They probably barely got high if they got high at all. So when the advocacy community tells them, you know, this is nothing, this is safer than alcohol, it’s safer than tobacco, the only reason it’s illegal is because cops want to arrest black people for it, the right thing to do is to legalize it and, by the way, we’ll get tax revenue and we’ll eliminate the black market, and crime will go down — well, if you haven’t used it and you’re not aware of all the science around it, these arguments all sound pretty good. It’s really up to the journalism community to stand up and say, hey, there’s a bunch of self-interested people here. Especially now that there’s a large for-profit industry around this that might have reasons to promote the use of this addictive smoked product, maybe we should actually look at what the science says. But nobody did that. I honestly should not have been able to write this book. This book comes out of some very profound failure in the national dialogue around cannabis.
CW: About the issue potency, one of the big takeaways from the email roundtable were you part of, coordinated by the Marshall Project, was that the fairly limited evidence we have on marijuana’s effects comes from studies of what one of the participants, Stanford psychiatry professor Keith Humphreys, called “old cannabis,” meaning the pot that’s been around for decades. That’s compared to what he calls the “new cannabis” that’s now being sold, which is several times stronger. We’re arguing over what we know and don’t know from studies that have been conducted. He’s kind of arguing that we know even less because we haven’t really had time to have studies of the marijuana that’s what’s going to be sold widely.
BERENSON: Yes. I think, if anything, my book probably underestimates the risks because most of the big studies are based on a cannabis that was not as potent and had more CBD [cannabidiol] in it. And there is some evidence that CBD, which is the other main chemical in cannabis, does at least counteract a little bit the effects of THC.
CW: You could easily read the National Academies report as urging more research on this connection of marijuana use and schizophrenia — the causal of direction of that association, they say, is unclear. But they also point out, just kind of as an aside, the fact that schizophrenia rates have remained pretty stable in some countries where marijuana use has increased a lot as another data point.
BERENSON: That may or may not be true. No one knows. No one knows what the schizophrenia rate is in the United States. The only places where they can count accurately, because they have good national health care systems, are in Denmark and elsewhere in Northern Europe. And those countries actually have shown an increase recently in schizophrenia diagnoses in the last 15 or 20 years. And those countries did see a pretty rapid increase in cannabis use in the ‘90s. You can no longer say there’s no evidence that schizophrenia rates are increasing in the West because now there is some evidence. There’s no evidence that schizophrenia rates are increasing, decreasing, going sideways, doing loops or anything else in the US because we don’t know what they are.
CW: The National Academies report also points to possible evidence of positive effects on cognitive function among some people with schizophrenia from marijuana use.
BERENSON: If you can find a psychiatrist who treats people with schizophrenia who encourages them to use cannabis or THC, please, please quote them. I mean that would be like finding a unicorn.
CW: You’ve done a lot of interviews and been in some of these round table conversations with researchers. One thing I’m struck by is that there are some people who’ve been critical of your book, like the writer for Vox [German Lopez] or Mark Kleiman, a drug policy researcher, but in both cases, those are people who actually say they’re with you in thinking marijuana’s dangers have been underplayed and underappreciated or studied. But they seem to say if the dangers have been underplayed, they think you’re overplaying your hand in the other direction.
BERENSON: I guess I’d say two things. They do have well-defined positions in favor of legalization. To me, somebody like Malcolm Gladwell or Stephanie Mencimer [author of an article on the book in Mother Jones], who are people I don’t know, they came at the book with no preconceived notion about legalization and they both found it convincing. And I think a lot of ordinary people who’ve read the book find it convincing. I think if you come at the book from the angle that legalization is definitely happening, you may find it frustrating. I would also say that I don’t believe the book overstates anything. It certainly doesn’t talk about any positive aspects of cannabis — that is true. But from my point of view, for 20 years, all we’ve heard are semi-mythical stories about the positive aspects of cannabis. I didn’t need to write that book. I need to write a book that tells you what you didn’t know.
CW: I was also going to ask about the question about marijuana as a gateway drug. Some critics of legalization have voiced this concern. Here in Massachusetts, the governor, the attorney general, and the mayor of Boston were all opposed to the ballot question legalizing it, and they voiced concerns about marijuana potentially serving as a gateway drug to use of more dangerous drugs. Legalization supporters say that’s essentially, you know, more Reefer Madness nonsense and they’ve kind of ridiculed that view.
BERENSON: There’s zero question that cannabis is a gateway drug. If you use cannabis, you’re much more likely to use, quote-unquote, harder drugs later. And that’s been demonstrated over and over and over again. The only question is why. Now you can argue that the reason is that because it’s illegal, you have to get it from a dealer and that dealer has heroin and cocaine and maybe your friends who were using it are also using heroin and cocaine and so you’re more likely to get in to those other drugs, too. That’s actually an argument for legalization. That’s basically what the Dutch, who are pretty reasonable people, believed 40 years ago. That was really why they legalized it. It’s interesting that the rest of Europe didn’t follow the Dutch. They’ve had a long time to see that experiment up close and didn’t follow the Dutch. The other argument is that there’s pharmacological properties to marijuana that prime your brain for other drugs and the experience of getting high – it makes people want to get high with other drugs. I suspect that both of those arguments probably have some validity, but the argument that cannabis use doesn’t usually predate other drug use is nonsense. Sometimes people say cannabis isn’t dangerous really in and of itself, but it is a gateway. That’s not what I believe. That’s not what the book argues. I think cannabis is plenty dangerous in itself.
CW: People always says they’re trying to bring these questions down to a matter of science and the strength of evidence and all those things, but the debate seems to have taken an ideological bent with your conclusions finding more favor with those on the right. Why is that?
BERENSON: Well, I think that’s very unfortunate. My book is not a political book. It’s a book about health and science. You can believe everything that’s in the book and still believe that cannabis should be legal because, you know, because you’re a libertarian or because you believe that the social justice arguments are so strong that nothing else matters. Or you believe that alcohol is legal and alcohol causes lots of violence and death, too. So it’s only fair that we have the same rules for cannabis. There’s lots of reasons that cannabis can be legal even if it causes psychosis and violence. What’s been really frustrating to me about the left’s point of view is that they don’t want to engage with the serious science. They want to scream “correlation is not causation” over and over again, or that I’ve somehow misunderstood the science. I have not misunderstood the science. To me, the left’s attitude towards this is a little bit like the hard right and climate change. This is what you do with a bunch of science that unfortunately doesn’t agree with the way you want the world to be. The left likes to think of itself as more evidence-based and more science-based. Maybe in this case we’re seeing the limits of that.
CW: You write that “the marijuana lobby brands itself as young, hip, and diverse. Cannabis activists are woke, seeing through government propaganda.”
BERENSON: I think they’ve done a great job and they’ve had the help of the elite media and they’ve had the help of Hollywood. My joke is that when I want to get psychotic, I don’t smoke pot. I watch “High Maintenance.” It’s on HBO. It’s about your friendly neighborhood pot dealer in New York City. This guy’s like the saint of marijuana. There’s an episode fairly recently where he delivers to a pregnant woman and then a teenage girl. Occasionally they sort of hint that there might be some problems with cannabis, but it’s all behind the screen of, “isn’t this a wonderful drug?” This is how this has been sold. It is no wonder there’s so much confusion about this.
CW: Can you talk a little about where this crosses over into questions about the criminal justice system and social justice because that has certainly been one of the powerful areas of pushback against what you’re talking about and the fact that you basically come down on the side that we should not be legalizing marijuana.
BERENSON: Sure. So I don’t think we should legalize it. I don’t think we should have a big industry around this marketing it to adults and, sort of subtly, to teens as for-profit companies that are marketing addictive substances will find ways to do. Forty million people used cannabis in 2017. We’re not going to put them all in prison. So we can have a decriminalized scheme. You know, you’re not going to be arrested for this. If you’re caught with this on the street, maybe you get a $25 ticket. You don’t get booked or anything like that. There’s a reasonable way to do this that eliminates or mostly eliminates the criminal justice issues. It is certainly true that black people and Hispanic people, especially black men, are more likely to get arrested for possession of cannabis than whites. It is also true that almost nobody of any race is in prison – I mean in prison, not arrested and held overnight, for cannabis possession. If we eliminated all cannabis arrests tomorrow, the criminal justice system would still have issues around race. Marijuana arrests do not cause racial disparities in the criminal justice system. They may worsen them slightly, but I’m not even convinced of that. As people have said to me, if cops want excuses to search young black men, they’ll find them. So this is more an effect than a cause.
CW: But hasn’t the horse left the barn at this point in terms trying to stop the legalization movement?
BERENSON: I strongly suspect yes. Certainly if a Democrat’s elected [president] in 2020, we’ll have full national legalization. There’s a lot of momentum for that.
CW: Just to sort of circle back on the issue of the overall risk, one of the problems often with any health risk is that we’re dealing with fairly small numbers. So even if there’s an increase in the risk, the vast majority of the people who smoke marijuana, even those who even smoke it regularly, will not develop schizophrenia as a result.
BERENSON: That’s certainly true. The fact actually is that schizophrenia isn’t that rare. Lung cancer in a population where there’s no smoking is extremely uncommon, while the rate ratio of lung cancer [the increased risk] in smokers versus nonsmokers is really high, right? It’s something like a 25 or 30 times greater risk. So that risk popped in such an obvious way that after a while nobody could deny it. This [schizophrenia] actually has a more common base risk and the relative risk, let’s say it’s two or three X. So that’s going to take a lot more work to get at. But at some point you’ve got to say, look, all the evidence actually points the same way. How many people need to get schizophrenia or get psychotic before we start to say, hey, at the least let’s put some serious warnings on this drug. To me that’s the ultimate question. The question is not, is this going to be legal or not? I don’t believe it should be legal, but more important than that the question is, are we going to warn people? Are we going to discourage this the way we discouraged tobacco use? Because tobacco is legal in this country and cannabis isn’t, but your 19-year-old is more likely to be using cannabis then tobacco. That’s a profound failure of the public health system.CW: Isn’t that sort of a function of the fact that we don’t have any agreement on even what the warnings should say? And also that this whole question of legalization has been very much conflated with the move toward criminal justice reform and questions about racial disparities in enforcing drug laws. So it has made it almost a social justice victory to see marijuana stores open.
BERENSON: That’s right. One of the crazier parts of this is that advocates are trying to get these stores in poor and minority communities. I think that’s so insane. I mean it was not very long ago that African-American and Hispanic political leaders were doing everything possible to get liquor stores and tobacco ads out of their communities. And somehow this has become a great victory. At best this is an addictive drug that reduces motivation for a lot of people.